J. Nannoplankton Res. 30 (1), 2008, pp.51-56 © 2008 International Nannoplankton Association, Inc.
ISSN 1210-8049 Printed by Cambridge University Press, UK

51

Three new species of calcareous nannofossil from Late
Palaeocene and Early Eocene assemblages (Ocean Drilling
Program Site 1262, Walvis Ridge, SE Atlantic Ocean)Claudia Agnini*, Eliana Fornaciari
Dipartimento di Geoscience, Università di Padova, Via Giotto 1, I-35137 Padova, Italy; *claudia.agnini@unipd.it

Isabella Raffi
Dipartimento di Geotecnologie per l’Ambiente ed il Territorio, Università ‘G. d’Annunzio’ di Chieti-Pescara, Via dei Vestini 31, I-66013 Chieti
Scalo, Italy
Manuscript received 10th January, 2008; revised manuscript accepted 18th May, 2008

Abstract At Ocean Drilling Program Site 1262 (Leg 208), a composite section spanning the Lower Palaeocene to
Lower Eocene was recovered from Walvis Ridge, eastern South Atlantic Ocean. Calcareous nannofossil assemblages
there are moderately to well preserved. Three new species have been identified: two new species of the genus Discoaster (D. backmanii, D. paelikei) and a new species of Sphenolithus (S. rioi) are described and illustrated.

Keywords Calcareous nannofossils, taxonomy, Discoaster, Sphenolithus, ODP Site 1262
1. Introduction
A high-resolution biostratigraphic study has been carriedout on Lower Palaeocene to Lower Eocene sediments from
Walvis Ridge (SE Atlantic Ocean), recovered during Ocean
Drilling Program (ODP) Leg 208 (Zachos et al., 2004). Detailed analysis of ODP Site 1262 (Agnini et al., 2007) revealed the presence of calcareous nannofossil specimensthat are not ascribable to previously formally-described
species. These new species, described below, are observedin different oceanic regions, suggesting that the new taxa
have a wide palaeogeographic distribution and thus may
potentially be useful in global biostratigraphic correlations.
Two of the new species belong to the genus Discoasterand one to the genus Sphenolithus. Besides the SE Atlantic
Ocean, the new Discoaster taxa have been observed in sediment cores recovered from the NW Atlantic and Pacific
Oceans and central-western Tethys. At ODP Site 1262,
these taxa showed similar stratigraphic positions, with respect to previous findings, and thus could be used to improve the available biostratigraphic framework.
The new species of Sphenolithus has been observed forthe first time in Walvis Ridge sediments, but further investigations record its presence also in Palaeocene sedimentsfrom north-eastern Italy and ODP Site 1209 (NW Pacific
Ocean), indicating a broad palaeogeographic distribution.
This new species, together with the coeval Sphenolithus
anarrhopus, is characterised by having a prominent apicalspine. The appearance of this morphologic feature represents a significant evolutionary change within the genus
Sphenolithus during Palaeocene times.
2. Material and methods
Calcareous nannofossil oozes from a Lower PalaeoceneLower Eocene carbonate-rich succession, recovered during ODP Leg 208, were analysed (Agnini et al., 2007). The

calcareous nannofossil assemblages are generally rich andmoderately well preserved. Specimens often show distinct
euhedral crystal faces from accretion of secondary calcite,
typical of carbonate chalk sediments. The early stages ofovergrowth begin to blur key diagnostic traits, however
recognition of the typical Discoaster and Sphenolithus features is guaranteed. Sediments from the Cicogna section(north-eastern Italy) and ODP Sites 1209 and 1215 (Pacific
Ocean) were also examined to determine the species’ spatial distributions.
Preparation of smear-slides followed the standard technique described in Bown & Young (1998). Norland 61 optical adhesive is used as a permanent mounting medium.
All samples were studied using a Zeiss Axioscope 40 transmitting-light microscope, under parallel and crossed-polarised light with 1250x magnification. The
photomicrographs were taken using the Zeiss Axioscope
40 and CamScan Mx 2500 scanning electron microscope.
The holotypes and paratypes are deposited in the permanent collection of the Museo di Geologia e Paleontologia
dell’Universitá di Padova (MGPD), Italy.
3. Systematic palaeontology
The higher taxonomic frameworks of calcareous nannofossils utilised are those of Young & Bown (1997a, b).
Order DISCOASTERALES Hay, 1977
Family DISCOASTERACEAE Tan, 1927
Genus Discoaster Tan, 1927
Discoaster backmanii sp. nov.
Pl.1, figs 1-6
1979 Discoaster sp.1 Okada & Thierstein: pl.5, fig.6; pl.15,
fig.11.

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Agnini, Fornaciari, Raffi

1985 Discoaster sp.1 Monechi: pl.10, fig.2.
Derivatio nominis: In honour of Jan Backman, full Professor at the Department of Geology & Geochemistry, University of Stockholm (Sweden), geoscientist, calcareous
nannofossil palaeontologist, and true friend.
Diagnosis: 5-7 rays, star-shaped, flat Discoaster with apoorly-developed central-area, lacking any prominent ornamentation. Although euhedral crystal faces of secondary
calcite could have partially obscured the morphologic features of D. backmanii, its simple morphology is most likely
original, rather than the result of massive overgrown.
Description: We adopt here the description of Okada &Thierstein (1979, p.523), who observed this discoasterid in
Atlantic Deep Sea Drilling Project (DSDP) Site 384 sediments and referred to it as Discoaster sp.1. It is a “medium
sized Discoaster with 5 to 7 thick rays whose inner parts
are joined together. The outer half of each ray is tapered
and terminates in cut off straight edges. The generally
straight rays are symmetrically arranged”. The rays are linear, and have a free length of 2/3 of the total ray length. No
knob is evident in the central-area, but deep sutures arepresent on both sides of the discoasterid. The sutures areasymmetrically arranged and broadly curved counterclockwise on one side, whereas they appear to be straighton the other side.
Differentiation: Discoaster backmanii differs from D.
okadai Bukry, 1981, which has longer and more slenderrays with pointed tips, and a very small central-area. D.
backmanii differs from D. nobilis Martini, 1961 and D. falcatus Bramlette & Sullivan, 1961, which have more serrated outlines, a greater number of rays and moredeveloped central-areas with a boss or a knob. A discoasterid form similar to D. backmanii has been described fromLower Eocene sediments by Brönniman & Stradner (1960),
who referred to it as D. geometricus. Although D. backmanii and D. geometricus are very similar, D. geometricus
has a more serrated outline and squat rays. The different
morphologies and stratigraphic ranges suggest considering
the two taxa as distinct species.
Holotype: Pl.1, fig.1.
Size: Longest dimension = 7-15μm (holotype = 14.3μm).
Paratype: Pl.1, fig.3; Sample ODP 208-1262B-17H-2W,
135-136cm.
Type locality: Walvis Ridge, SE Atlantic Ocean, ODP Leg
208, Site 1262.
Type level: Zone CP6, Thanetian (Upper Palaeocene);
Sample ODP 208-1262A-15H-5W, 64-65cm.
Range: CP6-CP7, Thanetian (Upper Palaeocene).
Remarks: The species was first recorded and described as
Discoaster sp.1 by Okada & Thierstein (1979) from theNW Atlantic Ocean (DSDP Leg 43, Site 384), and by Monechi (1985) from the NW Pacific Ocean (DSDP Leg 86,
Site 577). D. backmanii is the earliest representative of starshaped forms among the Discoaster genus that originate in
the Palaeocene. A phylogenetic relationship between D.
backmanii and D. okadai is suggested by the presence offorms with intermediate morphological features just before
the first occurrence (FO) of the new species.
Occurrence: Discoaster backmanii occurs consistently,
with high frequencies, in the interval between the FO of
Discoaster mohleri Bukry & Percival, 1971 and the FO of
D. multiradiatus Bramlette & Riedel, 1954, that is, in CP6CP7 (Palaeocene) of Okada & Bukry (1980). It has been
observed in the SE (Walvis Ridge) and NW (Sohm Abyssal
Plain) Atlantic Ocean, and in the NW Pacific Ocean(Shatsky Rise). At Site 1262, located on Walvis Ridge, thespecies is common to abundant in the upper part of CP6
and shows an abrupt decrease in abundance just below theFOs of D. okadai and the D. delicatus group. Very rare andscattered specimens of D. backmanii have also been observed in the lower part of the Lower Eocene (CP8-9a).
Discoaster paelikei sp. nov.
Pl.1, figs 7-14; Pl.2, figs 1, 2
1978 Discoaster sp.1 Proto Decima et al.: pl.12, fig.9; non
pl.12, figs 10, 11.
Derivatio nominis: In honour of Heiko Pälike, Reader at
the School of Ocean & Earth Sciences, National Oceanography Centre, University of Southampton (UK), geoscientist, palaeoceanographer, and person with natural
brightness.
Diagnosis: Star-shaped Discoaster with 5-6 (rarely 7) rays,
tapering toward pointed tips. The central-area is characterised by sutures curved clockwise on one side, whereas
the other side shows a flower-like knob. In 5-rayed specimens, rays can be slightly asymmetrical.
Description: A medium-sized Discoaster characterised bya quite delicate structure, with rays overlapping the inner
halves in the central-area on one side of the discoasterid.
The sutures curve toward the centre of the Discoaster,
showing a windmill-like structure. The outer half of each
ray is tapered and the free length of the rays varies from
1/2 to 2/3 of the total ray length.
Differentiation: A discoasterid form similar to D. paelikei
was described from Middle Eocene sediments by Stradner(1961), referred to as D. strictus, but D. paelikei differs in
the presence of windmill-like sutures, allowing easy morphological distinction between the two species. D. paelikei
differs from D. mahmoudii, which is characterised by aprominent, star-shaped knob and more slender rays. D. paelikei differs from D. okadai in having a more developed
central-area, squat rays and a prominent knob.
Holotype: Pl.1, fig.7.
Size: Longest dimension = 3.5-12μm (holotype = 11.4μm).
Paratype: Pl.1, fig.9; Sample ODP 208-1262A-13H-3W,
128-129cm.
Type locality: Walvis Ridge, SE Atlantic Ocean, ODP Leg
208, Site 1262.
Type level: Zone CP8b, Ypresian (Lower Eocene); Sample ODP 208-1262A-13H-3W, 128-129cm.
Range: CP8b, Ypresian (Lower Eocene).

New species, Palaeocene-Eocene, Walvis Ridge

53

Plate 1
Calcareous nannofossils from ODP Sites 1262 (Atlantic) and 1215 (Pacific) and from the Cicogna section (north-eastern Italy)
Scale-bars = 2μm (figs 1, 2) or 5μm (figs 3-14). BF = bright-field
SEM

Holotype, SEM

Discoaster backmanii Sample ODP 208-1262A-15H-5W, 64-65cm

BF

D. backmanii Sample ODP 208-1262A-15H-5W, 64-65cm

BF

BF

BF

D. backmanii Sample ODP 2081262B-17H-2W, 135-136cm

D. backmanii Sample ODP 2081262B-17H-2W, 135-136cm

D. backmanii Sample ODP 2081262B-17H-2W-135-136cm

D. backmanii Sample ODP 2081262B-17H-2W-135-136cm

Holotype, SEM

SEM

BF

BF

Discoaster paelikei Sample ODP
208-1262A-13H-3W, 128-129cm

D. paelikei Sample ODP 2081262A-13H-3W, 128-129cm

D. paelikei Sample ODP 2081262A-13H-3W, 128-129cm

D. paelikei Sample ODP 2081262A-13H-3W, 128-129cm

BF

D. paelikei Sample ODP 1991215B-7H-1W, 144-145cm

BF

D. paelikei Sample ODP 1991215B-7H-1W, 144-145cm

BF

D. paelikei Sample CIC/07-191,
Cicogna section

BF

D. paelikei Sample CIC/07-191,
Cicogna section

54

Agnini, Fornaciari, Raffi

Remarks: D. paelikei has a relatively short stratigraphic
range in the earliest Eocene. This species, together with D.
mahmoudii, is characterised by a distinctive morphology,
with respect to all the other discoasterids present in the calcareous nannofossil assemblages within CP8b.
Occurrence: D. paelikei occurs consistently in the lowermost Eocene, from the Palaeocene/Eocene boundary to thelast occurrence of Fasciculithus tympaniformis Hay &Mohler, 1967, in the lower part of CP8b. It has beenrecorded in the SE Atlantic Ocean (Angola Basin, DSDP
Site 364: Proto Decima et al., 1978; Walvis Ridge: thisstudy), Pacific Ocean (Site 1215, ODP Leg 199: Raffi, unpublished data; Site 1209, ODP Leg 198, Shatsky Rise: De
Bernardi, pers. comm., 2007) and north-eastern Italy (thisstudy).
Order DISCOASTERALES Hay, 1977
Family SPHENOLITHACEAE Deflandre in Grassé,
1952
Genus Sphenolithus Deflandre in Grassé, 1952
Sphenolithus rioi sp. nov.
Pl.2, figs 3-12
Derivatio nominis: In honor of our mentor, Domenico Rio,full professor at the Department of Geosciences, University of Padova (Italy), geologist and calcareous nannofossil palaeontologist.
Diagnosis: Medium-sized Sphenolithus with a prominent
apical spine, extending symmetrically from the basal part.
Description: The basal part is constructed of regularlyplaced calcite elements, and in crossed-polarised light(XPL), with the long axis at 0˚ to the nicols, has a squareshaped outline with equal quadrants. A solid, prominent,
straight apical spine extends symmetrically, with respect tothe basal elements. In XPL, with the long axis at 0˚ to thenicols, the basal part shows birefringence, whereas the apical spine has its maximum birefringence at 20-30˚ and 45˚to the nicols.
Differentiation: In the light microscope, S. rioi differsfrom S. anarrhopus (Pl.2, figs 13-16) in having a straight,
and generally longer, apical spine. S. rioi differs from S.
conspicuus Martini, 1976 in having a different apical spine:
S. rioi has a triangular-shaped spine, whereas S. conspicuus
is characterised by a slender, spearhead-shaped spine.
Holotype: Pl.2, fig.3.
Size: Height = 4.5-7μm (holotype = 6.7μm); width of base= 3.6μm; height of base = 2.1μm.
Paratype: Pl.2, figs 5-7; Sample ODP 208-1262A-15H3W, 128-129cm.
Type locality: Walvis Ridge, SE Atlantic Ocean, ODP Leg
208, Site 1262.
Type level: Zone CP6, Thanetian (Upper Palaeocene);
Sample ODP 208-1262A-15H-4W, 44-45cm.
Range: CP4-CP7, Upper Selandian-Thanetian (MiddleUpper Palaeocene).
Remarks: In previous studies, S. rioi has been probably

considered a morphotype of S. anarrhopus. The morphologic differences highlighted here are distinct enough towarrant taxonomic differentiation.
Occurrence: The FO of Sphenolithus rioi is recorded in
the upper part of CP4 (Upper Selandian). The species israre and scattered within CP5, whereas it is common andcontinuous in CP6 and CP7. The stratigraphic range of S.
rioi is virtually the same as for S. anarrhopus, with the FO
of S. rioi slightly predating the FO of S. anarrhopus.
Acknowledgements
This research used samples and data provided by the ODP. ODP
is sponsored by the US National Science Foundation (NSF) andparticipating countries under management of the Joint Oceanographic Institution inc. (JOI). CA, EF and IR were supported by
MIUR /PRIN COFIN 2005-2007, coordinated by I. Premoli Silva(national), Domenico Rio (Padova) and IR (Chieti). We would
like to thank Stefano Castelli for preparing plates of calcareous
nannofossils. A special thanks to Bianca De Bernardi for providing us with useful material. We are grateful to R.A. Denne, P.R.
Bown, S. Jiang and the Editor (J.A. Lees) for helpful comments.

References
Agnini, C., Fornaciari, E., Raffi, I., Rio, D., Röhl, U. & Westerhold, T. 2007. High-resolution nannofossil biochronology of
middle Paleocene to early Eocene at ODP Site 1262: implications for calcareous nannoplankton evolution. Marine Micropaleontology, 64: 215-248.
Bown, P.R. & Young, J.R. 1998. Techniques. In: P.R. Bown (Ed.).
Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series/Kluwer Academic Publishers, London, UK: 16-28.
Bramlette, M.N. & Riedel, W.R. 1954. Stratigraphic value of discoasters and some others microfossilis related to recent coccolithophores. Journal of Paleontology, 28: 385-403.
Bramlette, M.N. & Sullivan, F.R. 1961. Coccolithophorids andrelated nannoplankton of the early Tertiary in California.
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Deflandre, G. 1952. Classe des Coccolithophoridés (Coccolithophoridae Lohmann, 1902). In: P.P. Grassé (Ed.). Traité dezoologie. Anatomie, systématique, biologie, 1, part 1,
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New species, Palaeocene-Eocene, Walvis Ridge

55

Plate 2
Calcareous nannofossils from ODP Sites 1262 and 1209 and from the Cicogna section (north-eastern Italy)
Scale-bars = 5μm (figs 1, 2, 5-12, 14-16) or 2μm (figs 3, 4, 13). BF = bright-field, XPL = crossed-polarised light
BF

Holotype, SEM

BF

Discoaster paelikei Sample
CIC/07-191, Cicogna section

XPL, 0˚

D. paelikei Sample CIC/07-191,
Cicogna section

Sphenolithus rioi Side view, longspined morphotype. Sample ODP
208-1262A-15H-4W, 44-45cm

XPL, 30˚

XPL, 45˚

S. rioi Sample 1262A-15H-3W, 128-129cm

XPL, 30˚

SEM

S. rioi Side view, short-spined
morphotype. Sample ODP 2081262A-16H-1W, 132-133cm

XPL, 0˚

S. rioi Sample 1262A-15H-3W,
128-129cm

XPL, 0˚

XPL, 45˚

XPL, 45˚

11
S. rioi Same specimen as fig.8

S. rioi Sample 1209B-23H-4W, 1-2cm

SEM

XPL, 0˚

Sphenolithus anarrhopus Side
view, long-spined morphotype.
Sample ODP 208-1262A-16H-1W,
132-133cm

S. anarrhopus Sample 1262A-15H-3W, 128-129cm

XPL, 30˚

XPL, 45˚

56Agnini, Fornaciari, Raffi

Lethaea, 42: 1-41.
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Mesozoikum und Alttertiär. Erdöel-Zeitschrift, 77: 77-78.
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Wetenschappen te Amsterdam, 30: 411-419.
Young, J.R. & Bown, P.R. 1997a. Higher classification of calcareous nannofossils. Journal of Nannoplankton Research,
19: 15-20.
Young, J.R. & Bown, P.R. 1997b. Cenozoic calcareous nannofossil classification. Journal of Nannoplankton Research, 19:
36-47.
Zachos, J.C., Kroon, D., Blum, P. et al. 2004. Early Cenozoic Extreme Climates: The Walvis Ridge Transect. Proceedings of
the ODP, Initial Reports, 208. www-odp.tamu.edu/publications/208_IR/208ir.htm.